1. Technical Field
The present invention relates to a sterilization method and apparatus for sterilizing medical instruments and the like.
2. Description of the Related Art
Conventional sterilization apparatuses include those combining hydrogen peroxide with plasma, those combining ozone with plasma and those combining hydrogen peroxide with ozone.
As an example of sterilization with hydrogen peroxide plus plasma, JP Laid-open Application No. S61-293465 describes a sterilization method which includes a step of placing an object to be sterilized in a chamber, a step of keeping the object in contact with hydrogen peroxide for a time sufficient for the hydrogen peroxide to become closely involved with the object, a step of generating plasma around the object, and a step of holding the object in the plasma for a time required for sterilization.
JP Laid-open Application No. H1-293871 describes a sterilization method that includes a step of bringing an object to be sterilized into contact with hydrogen peroxide, a step of placing the object including residual hydrogen peroxide in a decompression chamber, a step of generating plasma around the object in the decompression chamber, and a step of holding the object in the plasma for a time sufficient to achieve sterilization by means of active species of the residual hydrogen peroxide.
JP Patent Publication 2003-533248 describes a plasma disinfection system wherein before plasma disinfection liquid hydrogen peroxide is first vaporized, and the hydrogen peroxide in a gaseous state is adjusted to the desired pressure and injected using a flow regulator.
JP Laid-open Application No. 2003-310720 describes a plasma sterilization apparatus provided with a sterilization chamber and a plasma generation chamber which communicates with the sterilization chamber so that plasma generated in the plasma generation chamber is supplied together with a sterilization agent to the sterilization chamber.
As an example of sterilization with ozone plus plasma, JP Laid-open Application No. 2003-159570 describes a sterilization and dry washing apparatus wherein oxygen or a mixed gas containing oxygen is subjected to discharge excitation within a treatment chamber housing an object to be treated to generate plasma, gaseous water molecules are sprayed, and the gas is exposed to ultraviolet rays.
JP Laid-open Application No. 2003-250868 describes a plasma sterilization processor wherein oxygen or a gas containing oxygen within a gas supply pipe is converted to plasma and supplied to a sterilization chamber, a gas supplied within the sterilization chamber is also converted to plasma, and these plasmas are contained by a magnet arranged within the sterilization chamber.
As an example of sterilization with hydrogen peroxide plus ozone, JP Laid-open Application No. 2002-360672 describes a sterilizer wherein hydrogen peroxide is first supplied to a treatment container which houses an object to be sterilized, and ozone is then added to the treatment container.
However, although all these conventional sterilization apparatuses are constructed so as not to leave residual harmful gas, their sterilization effects have not been adequate. The problem is that when the concentration of the sterilizing agent is raised to improve the sterilization effects, gas remains in the chamber after sterilization, and more time is required for breaking down the residual gas (aeration).